1. Field of the Invention
The present invention relates to a structure of a micromachine which is formed with a microelectromechanical system (MEMS) technology.
2. Description of the Related Art
These days, MEMS switches which utilize a MEMS technology, and sensors, resonators, communication devices, and the like which are provided with the MEMS switches have been attracting attention.
These are also called micromachines, and there are two kinds of technologies, a surface micromachining technology and a bulk micromachining technology, depending on manufacturing methods. In the surface micromachining technology, thin films are stacked over a substrate and then processed by a photolithography method or an etching method, whereby a MEMS structure body can be formed. Further, in the bulk micromachining technology, a silicon wafer or a silicon on insulator (SOI) substrate itself is processed by etching or polishing, whereby a MEMS structure body can be formed.
In particular, great importance is placed on the surface micromachining technology because a semiconductor process can be applied thereto. However, through the surface micromachining technology, a MEMS structure body has a three-dimensional structure in which thin films are stacked, and thus, a connection wiring which is formed at a step portion generated due to a thick layer (for example, a sacrificial layer) is easily thinned or disconnected; therefore, there is a problem in that the reliability of the wiring is significantly lowered.
Therefore, a method is proposed by which, in the case that a wiring is formed at a step portion generated due to a thick layer, the thick film is easily tapered with a given angle and the taper angle can more easily be controlled (for example, see Reference 1: Japanese Published Patent Application No. H7-66280).